topiramate, Topamax (cont.)

Pharmacy Author:

Omudhome Ogbru, PharmD

Omudhome Ogbru, PharmD

Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

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Medical and Pharmacy Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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Combining valproic acid (Depakote, Depakote ER, Depakene, Depacon, Stavzor) with topiramate may increase the blood ammonia levels and cause hypothermia (low body temperature).

Topiramate may decrease the amount of estrogen in the body in women taking oral contraceptives, possibly increasing the chances of unwanted pregnancy and breakthrough bleeding.

Patients with seizure disorders taking anticonvulsant medications, including topiramate, may develop nerve toxicity from a chemical, 4'-O-methylpyridoxine, found as a contaminant in some ginkgo preparations. Ginkgo should not be ingested by persons taking topiramate.

Topiramate may cause metabolic acidosis. Therefore, metformin (Glucophage), a drug which also causes metabolic acidosis, should should not be taken by patients receiving topiramate. Topiramate may increase lithium (Eskalith, Lithobid) levels at higher doses and lead to toxicity from lithium.

PREGNANCY: Topiramate has been associated with cleft palate in newborns whose mothers used topiramate during the first trimester of pregnancy.

NURSING MOTHERS: Topiramate is excreted in human milk at levels 10%-20% of the levels in the mother's blood.

SIDE EFFECTS: The most common side effects of topiramate are tiredness, dizziness, coordination problems, nervousness, nausea, weight loss, confusion, speech problems, changes in vision or double vision, tingling or prickling sensation in hands and feet, difficulty with memory, and sensory distortion.

Topiramate also is associated with increased blood levels of ammonia, metabolic acidosis, kidney stones, decreased sweating, and increased body temperature.

Topiramate may cause the sudden onset of vision and eye problems. Symptoms typically occur within the first month of therapy, with patients reporting an acute onset of decreased vision and/or eye pain. Eye examination revealed myopia (nearsightedness), redness, decreased depth of the anterior chamber of the eye and elevated ocular pressure, with or without dilation of the pupils. Fluid accumulation within the eye may displace the lens and iris anteriorly causing secondary angle closure glaucoma. If patients develop this syndrome, the treatment is to discontinue topiramate as rapidly as possible, according to the judgment of the treating physician.

 Antiepileptic medications have been associated with an increased risk of suicidal thinking and behavior. Anyone considering the use of antiepileptic drugs must balance this risk of suicide with the clinical need. Patients who are started on therapy should be closely observed for clinical worsening, suicidal thoughts, or unusual changes in behavior.

Reference: FDA Prescribing Information

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